The zebrafish, which has a morphological and molecular basis of tissue and organ development similar to that found in humans, is an ideal, vertebrate animal model for toxicity testing. In contrast to mice and rats, zebrafish are inexpensive to breed, undergo rapid embryogenesis and are easy to analyze because their embryos are transparent. Furthermore, drug delivery is simple and good dose responsiveness to toxicity has been observed. Currently zebrafish toxicity assays use lethality, embryo survival rate, behavior and microscopic examination of organ malformation as general parameters for assessing toxicity. However, for large-scale toxicity screening, qualitative visual inspection is not suitable. Using zebrafish embryos, this Phase I SBIR aims to develop a microplate-based ELISA assay to quantify liver toxicity. A rapid, quantitative assay for screening compounds for developmental organ toxicity will facilitate selection of lead compounds for further drug development. PROPOSED COMMERCIAL APPLICATIONS: By providing a rapid, quantitative, and inexpensive method for organ toxicity testing, the zebrafish assay will facilitate drug screening and toxicity testing in the pharmaceutical and chemical industries.